He's commenting on a survey that asked successful business leaders about their success. They said they focussed on simplicity in everything they did. The study concluded that focused companies were more profitable.
It's so easy to make things complicated for ourselves. In so many cases, the things you only spend 20% of your time on will account for 80% of your success. Doing a "lot" of things makes us feel productive, but doesn't necessarily increase our chance of success.
This is also true in managing software projects. There are only a handful of factors that throw most software projects off the rails - not hundreds. Manage these, and you'll do just fine.
Here are the ones I focus on:
1. Time Estimation Error - If you can't trust the estimates coming from the team, the project plan will never be accurate. There are ways to manage this.
2. Team Distraction Rates - If your plan doesn't account for the times the team is going to inevitably be pulled off the project, your plan will never be accurate.
3. Requirements - If you can't keep a handle on the requirements for the product you're building, or can't express the true impact of changing requirements while you're making those decisions to approve the change, your plan will never be right.
These ones are the secret to delivering software on time. Forget about critical path analysis, Pert charts and automated workload balancing. Projects don't fail because you didn't spend enough time looking at the critical path. They fail because the time estimates were wrong, people got pulled off the team, or requirements changed too much. Manage those.